This invention relates to glass fiber forming.
In one of its more specific aspects, this invention relates to temperature control of the bushings from which glass fibers are drawn.
In the formation of glass fibers, it is conventional to pull glass fibers through the apertures in the bottom of a molten glass container, or bushing. The glass depends from these apertures in the form of inverted cones and the fibers are drawn from these cones. The bushings can have tips, or be tipless.
Recently, it has been found that air introduction into the region of these cones and against the bottom of the bushing results in improved operations. However, it is also known that because of the non-uniform temperature of the molten glass within the bushing, there exists, even with air introduction, undesireably large differences in glass temperature at various zones of the bushing with attendant differences in the properties of the fibers which are drawn from those zones.
This invention is directed towards the solution of that problem.
By employment of the present invention, temperature differences between different loci of the bushing are maintained or eliminated with the result that filaments drawn from these loci are more uniform in properties or are of different properties. This is particularly beneficial when more than one package is formed from filaments drawn from a single bushing.